Zigmantas Donatas, Hiller Roger G, Sundstrom Villy, Polivka Tomas
Department of Chemical Physics, Lund University, Box 124, SE-22100 Lund, Sweden.
Proc Natl Acad Sci U S A. 2002 Dec 24;99(26):16760-5. doi: 10.1073/pnas.262537599. Epub 2002 Dec 16.
Carotenoids are, along with chlorophylls, crucial pigments involved in light-harvesting processes in photosynthetic organisms. Details of carotenoid to chlorophyll energy transfer mechanisms and their dependence on structural variability of carotenoids are as yet poorly understood. Here, we employ femtosecond transient absorption spectroscopy to reveal energy transfer pathways in the peridinin-chlorophyll-a-protein (PCP) complex containing the highly substituted carotenoid peridinin, which includes an intramolecular charge transfer (ICT) state in its excited state manifold. Extending the transient absorption spectra toward near-infrared region (600-1800 nm) allowed us to separate contributions from different low-lying excited states of peridinin. The results demonstrate a special light-harvesting strategy in the PCP complex that uses the ICT state of peridinin to enhance energy transfer efficiency.
类胡萝卜素与叶绿素一样,是光合生物中参与光捕获过程的关键色素。类胡萝卜素向叶绿素能量转移机制的细节及其对类胡萝卜素结构变异性的依赖性目前仍知之甚少。在这里,我们采用飞秒瞬态吸收光谱来揭示含有高度取代的类胡萝卜素——多甲藻素的多甲藻素 - 叶绿素 - a - 蛋白(PCP)复合物中的能量转移途径,该复合物在其激发态多重态中包括一个分子内电荷转移(ICT)态。将瞬态吸收光谱扩展到近红外区域(600 - 1800 nm)使我们能够区分多甲藻素不同低能激发态的贡献。结果表明,PCP复合物中存在一种特殊的光捕获策略,该策略利用多甲藻素的ICT态来提高能量转移效率。